In recent years, technology for changing the transmittance of a windshield of a vehicle has been developed for the purpose of protecting privacy within the vehicle or preventing an in-vehicle temperature from increasing when the vehicle is stopped.
In relation to this, an in-vehicle dimming control device for decreasing the transmittance of the entire windshield when the vehicle reaches a predetermined place and then increasing the transmittance of a position in contact with a finger or the like by the user is disclosed (see Patent Document 1). Further, in this in-vehicle dimming control device, control of the transmittance is permitted while the vehicle is stopped and the control of the transmittance is prohibited when the vehicle travels.